This invention relates to an automatic position controller for marine propulsion units and more particularly to an improved power unit for controlling the position of a marine propulsion unit and an automatic control device therefor.
It is well known to support an outboard drive such as an outboard motor or the outboard drive portion of an inboard/outboard drive on the transom of the associated watercraft for pivotal movement about a horizontally extending trim axis so as to adjust the trim of the propulsion unit. The desirable trim angle of the outboard drive varies with the watercraft running condition and such a mounting permits the outboard drive to be adjusted during operation to the optimum condition. Various types of powering devices have been employed for such trim adjustment. In addition, it is known that the vertical position of the power unit relative to the transom may be varied in order to provide the optimum relationship during different running conditions. For example, when the watercraft is accelerating, it is desirable to have the propulsion unit relatively deeply submerged. However, when the watercraft reaches a planing condition, the power unit should be elevated so that it is not so deeply submerged. Various power devices have been proposed for adjusting the degree of submersion of the outboard drive.
Clearly, the mounting of the power units for achieving trim and height adjustment present considerable problems. This is particularly true en it must be remembered that the power units are normally mounted outboard of the transom of the associated watercraft. Therefore, the power units are positioned in a location where they can easily become damaged.
It is, therefore, an object of this invention to provide an improved power unit mounting arrangement wherein the power units will be protected by their supporting structure from damage.
It is a further object of this invention to provide an improved and compact power unit arrangement for adjusting the vertical height of an outboard drive.
As has been noted, it is known that the height or vertical location of the power unit of an outboard drive should be varied under the watercraft running conditions. However, all of the power units for accomplishing vertical adjustment heretofore proposed have required manual operation. Therefore, with the prior art type of devices, it is solely within the control of the operator to select the vertical position and the operator may not be capable of sensing when the correct vertical position is reached.
It is, therefore, a further principal object of this invention to provide an improved power unit for automatically adjusting the vertical position of a marine propulsion device so as to achieve optimum running conditions.
It is a yet further objection of this invention to provide an improved control system for vertically positioning the power unit of a marine propulsion device.
It is a yet further object of this invention to provide an improved control arrangement wherein both of the vertical and trim conditions of the marine propulsion unit are controlled automatically so as to achieve optimum running conditions.
In connection with the provision of an arrangement for automatically controlling the vertical position and trim condition of a marine propulsion unit, there are certain running conditions under which it is desirable to achieve the tilt and trim adjustments in a specific sequence. For example, when accelerating from low speed, it is desirable to permit the vertical position of the outboard drive to remain relatively low in the water until the watercraft reaches a planing condition. Up until this time, the vertical position should not be changed but adjustment in the trim condition is desirable first to employ optimum acceleration and subsequently to maintain the cruising speed. Once the boat is in a planing condition, it is then desirable to raise the vertical position of the outboard drive so as to minimize water resistance of the lower unit and to improve stability.
It is, therefore, a still further object of this invention to provide an improved control arrangement wherein the trim and vertical conditions of a marine propulsion unit are controlled automatically and in the optimum relationship so as to achieve good running.